The present invention is directed to a method and device for counting flat objects such as folded boxes which are arranged in a flow of objects.
Several methods for counting folded boxes, which are moving in a flow of folded boxes, are already known. One of these is to skim an upper part of the flow of folded boxes with a detector finger connected to an electric switch or piezoelectric transducer. Such a counting device is described in the Swiss Pat. No. 588,994 and the counting operation is carried out on the top of the flow of vertically positioned folded boxes. The edges of the successive folded boxes are skimmed by a finger giving an impulse to a counting unit each time it passes over a box edge. The counting operation on such a flow is quite similar to the counting of a flow of overlapping folded boxes forming a flow of boxes arranged in a single like fashion. The upper part of the boxes in the flow that have a shingle-like relationship also show steps corresponding to the spaces between two boxes. Thus, the method in the Swiss patent can be adapted to counting objects in different flow arrangements.
Another commonly used method is to detect each box of a flow by means of a reader or sensor comprising a roller mounted on a lever which is connected to a microswitch. The output of the microswitch is connected to a counting unit or means. If the running speed of the flow remains quite low, these two methods perform very satisfactorily. However, with high speeds, the detecting finger or the roller have a tendency to jump over the folded boxes and the accuracy of the counting becomes very problematical.